If he had just been an asshole while drunk, it would still be shitty BUT some people are mean drunks and a boundary could have been set of "you need to not be intoxicated when speaking with me and my family". But his behavior while sober - well, LW, I hate to say it but you're better off not dealing with him. I feel like it's very telling that he's not on speaking terms with his kids.

Sometimes bio-families are not fixable - I'm there with my own bio-family and why I don't speak to them - and families of choice are the way to go. I know it hurts, LW, but it's time to let it go.